Ice packs are used to reduce swelling and inflammation in a local area; reducing pain by reducing the pressure of this swelling. If you are in a lot of pain try an icepack first – a bag of frozen peas wrapped in kitchen roll or a thin tea towel should do the trick!
Note; If you experience dizziness or any unusual symptom while using an ice pack on the neck, stop immediately.

If the pain is more moderate, warmth may be helpful in maintaining mobility and easing aching.

You can even alternate hot and cold packs approximately every 3 minutes for moderate inflammation and to encourage healing for things such as rotator cuff problems or healing ligament strains.